161 
Now, as far as L know, in a sense this is a tempest in a teacup oecause 
there is only one kind of plant pathogen whose DNA is being cloned at the 
moment in the country, and it is only going on in three labs, one of which 
is our lab, and this is the cloning experiments with the Agrobacterium Ti 
plasmid about which we have heard a little during this conference. This 
experiment was explicitly mentioned in the previous version of the Guide- 
lines and was explicitly designated as a P2+EK2 experiment. Now, suddenly 
in the middle of these experiments, I as an investigator am raced with the 
prospect of having to raise the level of containment for the self-same ex- 
periment. Last week it was P2+EK2, and next week it will be P3+EK2. I 
marvel at this. I find this an ironic situation. It seems that these clon- 
ing experiments are the only ones whose level of containment has been eleva- 
ted by the revised Guidelines. It seems as if we are talking out of both 
sides of our face in a way, because the very same agent, the Agrobacterium 
Ti plasmid has been invoked as part of the basis for the diminishing of the 
levels of containment of other experiments. The fact that the Ti plast.d 
seems to be capable of a little natural genetic engineering on its own — I 
do find this a rather ironic situation to face. 
If I could move on from that subject, do I have a couple of more minutes? 
DR. FREDRICKSON: Yes, you do, and may I ask you whether anybody has at- 
tempted to delete that tumor-producing gene from the Ti plasmid? 
DR. CHILTON: I believe there are naturally occurring deletions, yes, we 
have some . 
A second point that I would like to raise about the experimental Guide- 
lines that troubles me is the edict concerning the handling of naked recombi- 
nant DNA. The Guidelines dictate that the naked recombinant DNA should be 
handled with "good microbiological techniques, equivalent to those in a PI 
laboratory." Now, the implication is that novel recombinant DNA which comes 
out of a P4-containment cloning experiment can be disinfected and poured down 
the sink. And for example, a method of disinfecting would be to mix it with 
a phenolic agent. That is a good way of killing bacteria. This sort of step 
is commonly used in the isolation of pure biologically active transforming 
DNA. 
Now, it seems to me that we need to spell out exactly what we mean more 
carefully than it is stated in the Guidelines. The procedures that are re- 
commended in the Guidelines seem to allow a reasonable possibility of escape 
of novel recombinant DNA, considering the fact that transformation of several 
species of bacteria by naked DNA can occur in nature. It may seem unlikely, 
but nevertheless it seems to me that this sort of escape route is a lot more 
likely than the conjugat ional escape of 10' “ which has been bandied about 
and has been a concern of other speakers here today. 
So until we have data available which assess the probability of escape 
down the sink by naked transforming DNA, I think that it would be wise to 
be careful and to treat the recombinant DNA with agents that are known to 
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